Ink tubes are used in many printing devices, including thermal inkjet printers, piezoelectric inkjet printers, and other printing devices. Typically, these printing devices maintain a reserve of liquid ink in a reservoir. Ink tubes are used to transport the ink from the reservoir to the printing device's printhead or pens. The printhead, including individual pens, selectively deposits the ink onto a medium to create printed text and images. In most cases, ink tubes are made out of a flexible plastic material that allows for a substantially nonlinear path between the ink reservoir and the printhead.
Electronic control signals are generally transmitted from control circuitry in the printing device to electrical components in the inkjet pens. The control signals affect the operation of individual inkjet pens, such as when ink is selectively released from the pens onto print media. Wires or cables are generally used to electrically connect the control circuitry to the related components in the inkjet pens.
Additionally, some printing devices include diagnostic system components designed to aid service personnel in identifying faulty components. In some inkjet printers, for example, optical indicators such as light emitting diodes (LEDs) are used to indicate faulty inkjet pens.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.